File size obtained from Script is not the same as "Get Info" in Finder

Edit: I found more context on this problem and asked another question Calculate size of iOS framework using Swift script

I am creating a Swift script to calculate the size of a bunch of frameworks in my app. It seems to work, but the sizes don't add up.

In finder on a specific framework, Get Info shows 6,801 KB

In my script, I'm using this code to get the file sizes (with different keys):

  var bool: ObjCBool = false
  if FileManager.default.fileExists(atPath: documentsDirectoryURL.path, isDirectory: &bool), bool.boolValue {
    var folderSize = 0
    FileManager.default.enumerator(at: documentsDirectoryURL, includingPropertiesForKeys: [.<key_here>], options: [])?.forEach {
      folderSize += (try? ($0 as? URL)?.resourceValues(forKeys: [.<key_here>]))??.<key_here> ?? 0
    }

    return Int64(folderSize)
  }

I get 4,133 KB with fileAllocatedSizeKey & totalFileAllocatedSizeKey

I get 4,126 KB with fileSizeKey & totalFileSizeKey

According to the docs, the difference between these 4 keys has to do with metadata and the size vs allocated size. If I'm getting allocated size, why is there still 2-3 MB missing between these sizes?

PS: In this example the Finder version was bigger, but in many others the size calculated in the script is larger than the size from Finder.

I don't know what to trust!